Velocity control of a numerical control system

Claim 2

In a numerical control system having a plurality of servosystems for controlling a tool position along a plurality of mutually perpendicular axes, each servosystem controlling said tool position in a different one of said axes, a method for obtaining wholly withoUt human intervention a clock pulse train at a frequency which is a function of desired tool departure D, and in response thereto, obtaining departure pulses as a function of axis commands for each axis servosystem to move said tool at a predetermined velocity V, said method comprising: estimating said departure D from said axis commands; providing a train of pulses at a frequency which is a function of said velocity V and estimated departure D; and multiplying said train of pulses by said axis commands in pulse rate multipliers to obtain said departure pulses at a rate which provides said predetermined velocity V for the departure D.

Claim 3

A method as defined in claim 1 wherein said departure D is estimated in accordance with the equations the commands X and Y being interchanged in said equations if Y > X .

Claim 4

A method as defined in claim 2 wherein said departure D is estimated for a three-axes system by adding 0.3Z to each estimated departure from X and Y commands, where all conditions are satisfied as for a two-axes system, and interchanging X, Y and Z such that, as interchanged, X Y Z .

Claim 5

A method as defined in claim 1 wherein said train of pulses is provided at a frequency which is a function of said velocity V and estimated departure D by obtaining a voltage signal proportional to said estimated departure D, and applying said voltage signal to a voltage controlled oscillator which provides said train of pulses.

Claim 6

A method as defined in claim 1 wherein said train of pulses is provided at a frequency which is a function of said velocity V and estimated departure D by calculating a feedrate number FRN from the relationship defined by the equation V FRN.D, and multiplying pulses from a clock pulse source by said number FRN.

Claim 7

In a numerical control system having at least X and Y servosystems, the combination comprising: reading means for reading from a stored program axis commands X and Y for a predetermined departure D of a machine tool; a voltage controlled oscillator having a control terminal and an output terminal for producing a train of pulses at a frequency fo on said output terminal in response to a voltage signal; rate multiplier means connected to said reading means and said oscillator for producing departure pulses for said servosystems at frequencies fo.X and fo.Y; comparing means responsive to said departure pulses for determining whether said product frequency fo.X is greater than or equal to said product frequency fo.Y; dividing means responsive to said comparing means for dividing said product frequency fo.Y by 2 if said product frequency fo.X is greater than or equal to said product frequency fo.Y, and for dividing said product frequency fo.X by 2 if said product frequency foY is greater than said product frequency foX; combining means responsive to said dividing means for combining in an interspaced manner pulses of the divided frequency product with pulses of the undivided frequency product, whereby a train of pulses is produced at a frequency fs in accordance with the converting means responsive to said combining means for producing a voltage signal at said control terminal of said oscillator in response to said frequency fs, whereby said frequence fo is a function of an approximated departure D given by the equation

Claim 8

In a numerical control system having at least X and Y servosystems, the combination comprising: reading means for reading from a stored program axis commands X and Y for a predetermined departure D of a machine tool; a voltage controlled oscillator having a control terminal and an output terminal for producing a train of pulses at a frequency fo on said output terminal in response to a voltage signal; rate multiplier means connected to said reading means and said oscillator for producing departure pulses for said servosystems at frequencies fo.X and fo.Y; comparing means responsive to said departure pulses for determining whether said product frequency fo.X is greater than or equal to said product frequency fo.Y; dividing means responsive to said comparing means for dividing said product frequency fo.Y by 2 if said product frequency fo.X is greater than or equal to said product frequency fo.Y, and for dividing said product frequency fo.X by 2 if said product frequency foY is greater than said product frequency foX; combining means responsive to said dividing means for combining in an interspaced manner pulses of the divided frequency product with pulses of the undivided frequency product, whereby a train of pulses is produced at a frequency fs in accordance with the converting means responsive to said combining means for producing a voltage signal at said control terminal of said oscillator in response to said frequency fs, whereby said frequence fo is a function of an approximated departure D given by the equation

Claim 9

The combination as defined in claim 6 wherein said dividing means comprises: a first binary ciRcuit having a direct reset terminal connected to said comparing means, and a binary input terminal connected to said rate multiplier to receive said frequency product foX and remain set continually when foX foY, a second binary circuit having a direct reset terminal connected to said comparing means and a binary input terminal connected to said rate multiplier to receive said frequency product foY and remain set continually when foY<foX, and first and second gates connected to transmit said frequency products foX and foY, under control of said first and second binary circuits, respectively.

Claim 10

The combination as defined in claim 7 wherein said combining means comprises first and second flip-flops connected to be set by pulses transmitted by said first and second gates, respectively, and connected to be reset by said oscillator noncoincidentaly, and a multivibrator adapted to be triggered by said first and second flip-flops upon being reset.

Claim 11

In a numerical control system, the combination comprising: first means for reading from a stored program data for a desired machine tool departure D and a desired velocity V for said departure D; second means responsive to said first means for producing a first train of pulses at a frequency related to the product of a constant F and said velocity V; third means responsive to said first means for producing a second train of pulses at a frequency related to the product of said constant F, a number Q and said departure D; fourth means responsive to said second and third means for comparing said first train of pulses with said second train of pulses, and in response thereto, for producing a third train of pulses at a rate proportional to the difference in frequency between said first and second trains of pulses; and a counter for producing said number Q in response to said third train of pulses to increase said second train of pulses to the frequency of said first train of pulses at which time F.V F.Q.D, and Q FRN, where FRN is a feedrate number equal to the ratio V:D.

Claim 12

In a numerical control system, the combination comprising: first means for reading from a stored program data for a desired machine tool departure D and a desired velocity V for said departure D; second means responsive to said first means for producing a first train of pulses at a frequency related to the product of a constant F and said velocity V; third means responsive to said first means for producing a second train of pulses at a frequency related to the product of said constant F, a number Q and said departure D; fourth means responsive to said second and third means for comparing said first train of pulses with said second train of pulses, and in response thereto, for producing a third train of pulses at a rate proportional to the difference in frequency between said first and second trains of pulses; and a counter for producing said number Q in response to said third train of pulses to increase said second train of pulses to the frequency of said first train of pulses at which time F.V F.Q.D, and Q FRN, where FRN is a feedrate number equal to the ratio V:D.

Claim 13

The combination as defined in claim 9 wherein said tool departure data is read by said first means as axis commands X and Y, and said third means includes means responsive to said axis commands for determining said departure D from said axis commands.

Claim 14

The combination as defined in claim 10 wherein said determining means computes said departure in accordance with the equations

Claim 15

The combination as defined in claim 11 wherein said determining means computes said departure D in accordance with the equations the commands X and Y being interchanged in said equations if Y > X .

Claim 16

The combination as defined in claim 12 wherein said determining means computes said departure D for a three-axes system by adding 0.3Z to each estimated departure from X and Y commands, where all conditions are satisfied as for a two-axes system, and interchanging the denomination of X, Y and Z such that, as interchanged, X Y Z .

Claim 17

In a numerical control system, the combination comprising: means for reading axis commands from a stored program for a predetermined departure D of a machine and a corresponding velocity V for the departure D; means connected to receive said axis commands and compute the departure D; a first rate multiplier connected to receive said velocity V and a train of pulses at a given constant frequency F to produce an output train of pulses at a reference frequency which is a function of velocity V; a second rate multiplier connected to receive a number Q and an input train of pulses at said given constant frequency F to produce a train of pulses at a frequency which is a function of the number Q; a third rate multiplier connected to receive said departure D and said output train of pulses from said second rate multiplier to produce an output train of pulses at a frequency which is a function of said departure D and said number Q; means for comparing the frequency of said output train of pulses from said first velocity rate multiplier with the frequency of said output train of pulses from said third rate multiplier, and for transmitting a train of pulses at a rate proportional to the difference in frequency; and a counter for providing said number Q connected to receive said train of pulses from said comparing means whereby said number Q is increased until the multipliers of said first, second and third multipliers bear the relation V Q.D, at which time Q is equal to a feedrate number necessary to multiply a clock frequency to obtain a pulse train at a frequency proportionate to the ratio of velocity V to departure D for machine tool motion of said desired velocity V.

Claim 18

In a numerical control system, the combination comprising: means for reading axis commands from a stored program for a predetermined departure D of a machine and a corresponding velocity V for the departure D; means connected to receive said axis commands and compute the departure D; a first rate multiplier connected to receive said velocity V and a train of pulses at a given constant frequency F to produce an output train of pulses at a reference frequency which is a function of velocity V; a second rate multiplier connected to receive a number Q and an input train of pulses at said given constant frequency F to produce a train of pulses at a frequency which is a function of the number Q; a third rate multiplier connected to receive said departure D and said output train of pulses from said second rate multiplier to produce an output train of pulses at a frequency which is a function of said departure D and said number Q; means for comparing the frequency of said output train of pulses from said first velocity rate multiplier with the frequency of said output train of pulses from said third rate multiplier, and for transmitting a train of pulses at a rate proportional to the difference in frequency; and a counter for providing said number Q connected to receive said train of pulses from said comparing means whereby said number Q is increased until the multipliers of said first, second and third multipliers bear the relation V Q.D, at which time Q is equal to a feedrate number necessary to multiply a clock frequency to obtain a pulse train at a frequency proportionate to the ratio of velocity V to departure D for machine tool motion of said desired velocity V.

Claim 19

In a numerical control system, the combination comprising: first means for reading from a stored program numerical data for a desired machine tool departure D and a desired velocity V for the departure D, wherein said velocity is represented by a code f(abc) where the ''''a'''' is a coefficient of a multiplier Ra p for the balance of the code representing a fraction (.bc), where R is the radix of said numerical data and p is a constant; second means responsive to said first means for producing a first train of pulses equal to the produce of a constant F and said fraction (.bc); third means responsive to said first means for producing a second train of pulses equal to the product of said constant F, a number Q, said departure D and said multiplier R1 p inverted; fourth means responsive to said second and third means for comparing said first train of pulses with said second train of pulses, and in response thereto, for producing a third train of pulses at a rate proportional to the difference in frequency between said first and second trains of pulses; and a counter for producing said number Q in response to said third train of pulses to increase said second train of pulses to the frequency of said first train of pulses at which time F.V F.Q.D, and Q FRN, where FRN is a feedrate number equal to the ratio V/D.

Claim 20

In a numerical control system, the combination comprising: first means for reading from a stored program numerical data for a desired machine tool departure D and a desired velocity V for the departure D, wherein said velocity is represented by a code f(abc) where the ''''a'''' is a coefficient of a multiplier Ra p for the balance of the code representing a fraction (.bc), where R is the radix of said numerical data and p is a constant; second means responsive to said first means for producing a first train of pulses equal to the produce of a constant F and said fraction (.bc); third means responsive to said first means for producing a second train of pulses equal to the product of said constant F, a number Q, said departure D and said multiplier R1 p inverted; fourth means responsive to said second and third means for comparing said first train of pulses with said second train of pulses, and in response thereto, for producing a third train of pulses at a rate proportional to the difference in frequency between said first and second trains of pulses; and a counter for producing said number Q in response to said third train of pulses to increase said second train of pulses to the frequency of said first train of pulses at which time F.V F.Q.D, and Q FRN, where FRN is a feedrate number equal to the ratio V/D.

Claim 21

The combination as defined in claim 15 wherein said tool departure data is ready by said first means as axis commands X and Y, and said third means includes means responsive to said axis commands for determining said departure D from said axis commands.

Claim 22

The combination as defined in claim 16 wherein said determining means computes said departure in accordance with the equations

Claim 23

The combination as defined in claim 17 wherein said determining means computes said departure D in accordance with the equations the commands X and Y being interchanged in said equations if Y > X .

Claim 24

The combination as defined in claim 18 wherein said determining means computes said departure D for a three-axes system by adding 0.3Z to each estimated departure from X and Y commands, where all conditions are satisfied as for a two-axes system, and interchanging the denomination of X, Y and Z such that, as interchanged X Y Z .

Claim 25

The combination as defined in claim 15 Wherein: said third means comprises a rate multiplier having m+n orders, m is the number of digits of said multiplier Q and n is the maximum difference a-p permitted in the coefficient of the multiplier Ra p, said rate multiplier having a switch means responsive to said code ''''a'''' for receiving a train of pulses at a frequency F for multiplication by the contents of said counter, said switch means being adapted to switch said train of pulses to different multiplier orders according to said difference a-p such that said rate multiplier includes a number of orders equal to m plus said difference a-p; and said counter has a number of cascaded orders equal to m+n, said counter having a switch responsive to said code digit ''''a'''' for receiving said third train of pulses from said fourth means such that said counter receives said third train of pulses at the input of m cascaded decades thereof which provide multiplier digits to the corresponding n orders of said rate multiplier having the greatest weight, the most significant of which is the rate multiplier order to which said switch means is currently connected in response to said code ''''a.''''

Claim 26

The combination as defined in claim 20 including: a linear interpolator connected to receive axis commands and in response thereto produce trains of pulses proportionate to the product of the axis commands and the content of said counter when the rate of said third train of pulses has been decreased to zero; a source of clock pulses; a feed generating pulse rate multiplier having m+n orders connected to receive clock pulses from said source at the most significant stage; and a latching transfer network for transferring the contents of said counter to said feed generating pulse rate multiplier as the multiplier thereof, whereby said linear interpolator receives said clock pulses multiplied by the contents of said counter as a feedrate number equal to the ratio V/D.

Claim 27

A method as defined in claim 1 wherein said departure D is estimated from axis commands X and Y in accordance with the equation

Claim 28

In a numerical control system having a plurality of servosystems for controlling a tool position along a plurality of mutually perpendicular axes, each servosystem controlling said tool position in a different one of said axes, apparatus for obtaining a clock pulse train at a frequency which is a function of desired tool departure D, and in response thereto, obtaining departure pulses as a function of axis commands for each axis servosystem to move said tool at a predetermined velocity, said apparatus comprising: means for estimating said departure D from said axis commands; means for providing a train of pulses at a frequency which is a function of said velocity V and estimated departure D; and a plurality of means for multiplying said train of pulses by said axis commands, one multiplying means for each axis command, to obtain said departure pulses at a rate which provides said predetermined velocity V for the departure D.

Claim 29

In a numerical control system having a plurality of servosystems for controlling a tool position along a plurality of mutually perpendicular axes, each servosystem controlling said tool position in a different one of said axes, apparatus for obtaining a clock pulse train at a frequency which is a function of desired tool departure D, and in response thereto, obtaining departure pulses as a function of axis commands for each axis servosystem to move said tool at a predetermined velocity, said apparatus comprising: means for estimating said departure D from said axis commands; means for providing a train of pulses at a frequency which is a function of said velocity V and estimated departure D; and a plurality of means for multiplying said train of pulses by said axis commands, one multiplying means for each axis command, to obtain said departure pulses at a rate which provides said predetermined velocity V for the departure D.

Claim 30

In a numerical control system, apparatus as defined in claim 23 wherein said estimating means responds to X and Y commands in accordance with the equation

Claim 31

In a numerical control system, apparatus as defined in claim 23 wherein said means for providing said train of pulses at a frequency which is a function of said velocity V and estimated departure D comprises means for obtaining a voltage signal proportional to said estimated departure D, a voltage controlled oscillator, and means for applying said voltage signal to said oscillator as a control voltage.

Claim 32

In a numerical control system, apparatus as defined in claim 23 wherein said means for providing said train of pulses at a frequency whiCh is a function of said V and estimated departure D comprises means for calculating a feedrate number FRN from said velocity V and estimated departure D in accordance with the relationship defined by the equation V FRN.D, a source of clock pulses at a constant frequency, and means for multiplying clock pulses from said source by said number FRN.